1. Field of the Invention
The present invention relates to an apparatus for hinging together the housings of foldable devices, and particularly to an apparatus for hinging together the housings of a foldable mobile phone.
2. Description of Related Art
Portable radiotelephones having two housings joined by a type of hinge that allows the housings to fold upon one another are known in the art. Some such folding radiotelephones have most of the electronics in one housing, called the main housing, and fewer electronics in the other housing, called the cover. Other such folding radiotelephones have all the electronics in the body, with the cover serving only to cover the keypad or the keypad and the display of the radiophone. Manufacturers have tried to reduce the volume, size and weight of the portable radiotelephone. Thus, it is desirable that the hinge coupling the main housing with the cover is modularized and miniaturized. The modularized hinge device is required to have the structure for holding moving parts of the hinge, such as a cam member, a cam follower and a spring. For miniaturization, the size and the number of parts of the hinge should be reduced.
Such a hinge assembly is disclosed in U.S. Pat. No. 6,085,387, as shown in FIG. 5. The hinge assembly has a can 21, a first hinge member 22, a second hinge member 23 and a spring 24. The first hinge member 22, the second hinge member 23 and the spring 24 are inserted into the can 21 with an open end 217 of the can 21 being partially covered by way of bending protrusions 213 of the can 21. The first hinge member 22 is inserted through the open end 217 of the can 21, with a shaft 222 of the first hinge member 22 extending through a hole 211 of the can 21. The second hinge member 23 is inserted trough the open end 217 of the can 21 so that two protrusions 223 of the first hinge member 22 can be engaged with peaks 235 and valleys 236 of a earn portion 233 of the second hinge member 23, and a cylindrical guide column 234 is located between the two protrusions 223 for guiding the relative motion between the first and second hinge members 22, 23. The spring 24 exerts the elastic force on the second hinge member 23 to push the second hinge member 23 toward the first hinge member 22. However, the cylindrical guide column 234 may deviate from the rotating axis during rotation, so that the second hinge member 23 cannot smoothly and stably move relative to the first hinge member 22. Furthermore, it is hard to keep the spring 24 moving longitudinally, since there is no longitudinal support or guide member for fixing the spring 24. Thus the spring 24 can be easily damaged, and the second hinge member 23 cannot smoothly and stably move relative to the first hinge member 22.
Therefore, an improved hinge assembly which overcomes the disadvantages of the prior art is desired.